This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 1022 |
| 3 | 59046 |
| 4 | 1048572 |
| 5 | 9765620 |
| 6 | 60466170 |
| 7 | 282475242 |
| 8 | 1073741816 |
| 9 | 3486784392 |
| 10 | 9999999990 |
| 11 | 25937424590 |
| 12 | 61917364212 |
| 13 | 137858491836 |
| 14 | 289254654962 |
| 15 | 576650390610 |
| 16 | 1099511627760 |
| 17 | 2015993900432 |
| 18 | 3570467226606 |
| 19 | 6131066257782 |
| 20 | 10239999999980 |
| 21 | 16679880978180 |
| 22 | 26559922791402 |
| 23 | 41426511213626 |